A retirement letter should have a heading that includes the current date, the name and company title of the individual, company email address, as well as the actual address within the company, according to About.com. The letter should be addressed to the immediate supervisor. The letter should also contain a formal thank you to the company for its support and employment for the years worked there. The individual should also offer to help in any way necessary to prepare a replacement.

This type of letter also provides a hard date to the human resources department so the department can assist the individual with any sort of financial transitions that may be necessary, such as applying for Social Security, explains About.com. This letter should be signed by hand, as well as having a typed signature. This type of letter should be considered a formal conclusion to a career with that company, and it should be written as such. Any personal feelings toward individuals or policies should not be included in this document.